I cut all my hair off with safety scissors like those when I was 4. My dad fell asleep while my mom was out shopping and I was playing beauty shop.
"In my day..." LOL we didn't have the advantage of rounded edges. However, it is most likely a very good idea for this generation and perhaps the one before. It's not that you don't have to keep an eye on your young ones, you do, but it's sort of one less thing to worry about :)